The present invention relates to a temperature sensitive fan drive which is called also a fan coupling, a fan clutch, a fan clutch drive, or a fan drive, and more particularly to a temperature sensitive fan drive which is used in a cooling fan that is disposed immediately behind a radiator and rotated by an engine, and that, even when an automobile is stopped and the vehicle wind is not expected, ventilates the radiator so as to ensure the heat radiation performance of the radiator. Such a fan drive controls the rotation of the fan in accordance with the temperature of the air.
A conventional temperature sensitive fan drive of such a kind is well-known by, for example, U.S. Pat. Nos. 5,232,074, 5,452,782, and 5,501,183, which has a structure in which a casing is rotatably supported on a drive shaft via a ball bearing or a needle bearing. Lubrication of the ball bearing or the needle bearing is performed by means of grease. When such a fan drive is used for a long term under severe conditions, therefore, there is a fear that seizure of the bearing occurs. In this way, the life of a bearing is affected by service conditions.